Auto-generators of hot gases under pressure, and in particular in free piston auto-generators



March 5, 1957 H. HORGEN 2,783,750

AUTO-GENERATORS OF HOT GASES UNDER PRESSURE, AND IN PARTICULAR IN FREE PISTON AUTO-GENERATORS Filed July 20, 1955 United States Patent AUTO-GENERATORS 0F HOT GASES UNDER PRESSURE, AND IN PARTICULAR IN FREE PISTON AUTO-GENERATORS Helge Horgen, Lyon, France, assignor to Societe tlEtudes et de Participations, Eau, Gaz, Electricite, Energie, S. A., Geneva, Switzerland, a society of the Confederation of Switzerland Application July 20, 1953, Serial No. 369,147 Claims priority, application France January 30, 1953 2 Claims. (Cl. 123-46) generally the whole of it serving to the feeding and the scavenging of the power portion. This power portion supplies, through its outlet orifices, gases under pressure constituted by scavenging air mixed with the combustion I gases uncompletely expanded in the power portion.

My invention is more especially but not exclusively concerned with such auto-generators having free pistons, that is to say including pistons at least one of the dead center positions of which is variable. The invention is still more particularly concerned with auto-generators the compressor portion of which compresses air during the inward stroke of the piston, that is "to say during the stroke which constitutes for the power portion the compression stroke, the air thus compressed being discharged, beforethe end of said inward stroke, directly into a reservoir adjacent to this compressor portion and which generally surrounds the cylinder of the power portion, whereby this reservoir constitutes the casing of the machine.

The chief object of my invention is to provide a machine vof the type above referred to which is better adapted than those existing up to the present time to meet the requirements of practice.

According to my invention, means for cooling the air intended for the feeding and scavenging of the power portion cylinder are provided, .and these cooling means are arranged to act upon this air while it is flowing from the discharge of the compressor portion to the intake of the power portion.

Another feature consists in disposing, inside the above mentioned casing, opposite the intake openings of the power portion cylinder, cooling means which serve to cool not only the air which enters this cylinder but also the hot combustion gases which might escape through said intake orifices toward the inside of the casing.

- Preferred embodiments of my invention will be hereinafter described with reference to the accompanying drawings, given merely by way of example, and in which:

Figs. 1 to 4 diagrammatically show in longitudinal section a simple auto-generator having opposed free'pistons and made according to four embodiments of my invention respectively;

Fig. 5 shows a double auto-generator constituted by the combination of two simple auto-generators, this double auto-generator being made according to another embodiment of my invention.

In the following description, it will be supposed that the free piston auto-generator is arranged so that air is compressed during the inward stroke of the compressor clement.

I s 4 Such an auto-generator includes, in known fashion, a

power cylinder 1 in which are fitted two power pistons 2 having opposed movements. The displacements of these two pistons are kept in synchronism by means of a conventional synchronizing mechanism which is not shown by the drawings. These power pistons, when they are close to their outer dead center position, open inlet ports 3 and outlet ports 4 provided in the wall of power cylinder 1, it being supposed as it is generally the case that the power portion of the machine works on the two-stroke diesel cycle. Fuel is injected when the power pistonsZ are close to their inner dead center position, by means of one or several injectors disposed in the transverse middle 7 plane of the machine and which are not shown by the drawings. v a I p The power portion which has just been described is disposed inside a casing 5 through which extends an ex haust conduit 6 in communication with theldischarge orifices 4 of the power cylinder 1.

Each of the power pistons 2 is rigid with a compressor piston 7 and each of these compressor pistons is working in a cylinder 8. The two cylinders 8 are located on either side of casing 5 and each of them is separated from this casing by a partition 9. Each cylinder 8 is divided into two chambers by the com ressor piston 7 present therein,

Each chamber 8a constitutes the compressor cylinder proper where air drawn into this chamber through valves 10 is compressed during the inward. stroke of pistons '2- 7,

this air being discharged at the end of this stroke through,

discharge valve into casing 5. r

The outlet chambers of said cylinders 8 contain air cushions which store up energy during the outward stroke of pistons 27 (taking place under the effect 'of the combustion of fuel in power cylinder 1) and give'b'ack this energy to pistons 72 during the inward stroke, thereof so as to make this last mentioned stroke possible.=

It is well known that the power of a given autogenerator is essentially determined by the temperatures of the hot gases under pressure which flowout from'the. generator through exhaust conduit 6, and which, are constituted by scavenging air which has flown throughpower cylinder and by the combustion gases which have mixed with this scavenging air and the pressure of which correproposed to cool down the air, during its travel from the blower to the intake of the compressor cylinder of -the auto-generator. pro-compressing of the air before its entrance into the compressor cylinder of the auto-generator and in view,

consequently, of the slight increase of temperature of said air due to pro-compression, a really efficient cooling of this air would have required rather complicated installa tions which would have considerably increased the cost and the dimension of the auto-generator. Furthermore;

this known arrangement was applicable only when the'. compressor cylinder or cylinders of the auto-generator.

was or were fed with precompressed air.

In order to avoid these drawbacks and according to the main feature of my invention, cooling means are provided which act upon the air compressed by the compressor portion 7-811, on its way from the discharge of saidcompressor portiontoward the intake of the power cylin-' der of the power portion.

I thus obtain a very efiicient cooling eflec't by making Patented Mar. ,5, 195,7

However, in view of the relativelyllow.

sesame use. of relativelysiniple"cooling means, which do not increase the volume of the auto-generator or atdeast in crease it but very little.

I Of course, such an arrangement can be made in many different 'ways. 'Sevelialembodiments of such an auto-generator new bejdscribed' with reference to the drawingsu All these embodiments, are concerned with an auto-generator th'compressor portion of which compresses air during the inward stroke of the piston and discharges this air directly into the casing adjacent to the compressor cylinder.

Iiiorder to cool'down the compressed air present in the cas ings of the auto-generator, I may surround this casing,"asshown by Fig. 1, with a cooling jacket 12 through which a'cooling liquid flows, for instance cooling water, which enters this jacket at 13 and leaves it at 14. Thus the outer envelope of the casing, which has a large area, is used directly. Such a cooling is not very expensive and it has further for its eifect to limit the danger of ignition in the casing. Furthermore, i obtain that the cite-mat surfaces of the machine are at a moderate tempe'r'atiirei' Tnth'e embodiments'shown by Figs. 2, 3 and 4, I cause the air under pressure which is circulating in the casing t'o-flow' along a cooling device constituted, for instance, by a coil in which a cooling liquid is caused to flow. Theenergy necessary for this air circulation is supplied, in the auto-generators illustrated by Figs. 2 and 3, by the compressor-pistons 7 themselves, during the strokes thereof which discharge the compressed air into the casing. Thus, in the construction illustrated by Fig. 2, the inside of the casing is divided into two chambers, by a transverse partition 16 located between the inlet ports 3 and the exhaust ports 4 and very close to the inlet ports 3.

Furthermore, the two chambers thus formed inside casing 5 are connected with a space 17 inside which the cooling coil 15 is located. With such an arrangement, a substantial portion of the air discharged past valves 11,

during the inward stroke of pistons 7 is compelled to come. into space 17; When one of the power pistons 2 clears ports 3 the air present in this space 17 and even a portionof the air present in the chamber of the casing which is located on the sid'e' of the exhaust ports 4 enter powercylinder 1, after having flown along the outer walls of cooling coil 15. p a I V In the construction iilustrated'by Fig. 3, the space 17 inside which is located cooling coil 15 communicates at one .of its ends with the inside of casing 5 through a valve 18 which opens only in the direction from the casing toward space 17, and at the other end, through a valve 19 which opensonly in the opposite direction. Preferably, valve'1'8 is located on the side of the exhaust ports 4 of cylinder 1 and valve 19 a the side of the inlet ports 3 of thisicylinder. When compressed air is discharged from the compressor cylinder into casing 5, a portion of this air enters space 17, through valve 18, and flows out therefrom after cooling, through valve 19, when one of the power. pistons 2 clears the inlet ports 3. A portion of the air therefore flows along the path shown in Fig. 3 by the arrows.

In the auto-generator shown by Fig. 4, a movement of air along cooling coil '15 is obtainedby means of a fan 20 driven for instance by an electric motor 21. Space 17 Communicates at both of its ends constantly with. the inside. of casing 5. Fan 20 creates an air flow along cooling coil 15 and the direction of this air flow is advantageously that illustrated in Fig. 4 by the arrows.

. The use of an external source (fan 20 and motor 21) to;pi'o.duce the air circulation along cooling coil 15- has the advantage of an easy adjustment of the cooling effect. AS a matter-of fact, this adjustment may be obtained by adjusting. the speed of the fan. It is thus possible to obtain air at a maximum temperature which is a'pproxi mately constant. a

will

My invention is particularly easy to carry out when the auto ge'nerator to" which his applied *is a" twinauto generator, that is to say is obtained by combining two simple auto-generators A and B, the casings 5A and 5B of which are connected together by a conduit 22 and the pistons of which work with the same number of strokes per unit of time and in. phase opposition of about that is'to'say so that when the pistons of one of thetwo generators, for instance generatorA,- are in their inner dead center position, the pistons of the other generator B are in their outer dead cent'er position; 7

in such anauto-gener'ator, the air for scavenging and feeding thc'power cylinder of one of thetwo'elementa'ry auto-generators is supplied at least partly from the'c'o'mpressor portion of the other auto-generator, andinversely. in communication conduit 22, there is an air stream which changes-its direction of flow" after every half-stroke of the pistons of the two "elementary auto-generators.

According to my invention, the cooling means are for instance constituted by a coil 23 placed inside communication conduit" 22. The' fact that the air stream to" be cooled and which flows alongsaid cooling element has a direction which is constantly changing is favorable to the exchange of calories and prevents the depositing of impurities;

It should be noted that the cooling efiect obtained with the device illustrated by Fig. 5 might be adjusted by providing a by-pass conduit parallel to conduit 23 and extending between the two generators A and B; this by-pa'ss conduit would be fitted witha control device constituted for instance by a mere shutter or valve the position of which would determine the ratio of the amounts of air flowing on the one hand through conduit 23 provided with cooling means and, on the other hand, through the" by-pass conduit in question which would not be provided with cooling means.

Of course, it should be well understood that my invert: tion also applies to the case of an auto-generator having a compressor portion arranged to discharge the coni= pressed air during the outward stroke of the piston thereof and where the cooling means would be inserted in the conduit conveying the air discharged by the compressor portion toward the casing.

My invention also applies to the case where a stream of cold air coming from an additional blower and driven for instance by a secondary turbine would be blown into the casing.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and eflicient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. An auto-generator of hot gases under pressure which comprises, in combination, two elementary auto-genera tors including each at least one internal combustion power cylinder provided with at least one air intake port and one exhaust port, a power piston freely movable in said cylinder, means for collecting the hot gases under pressure from said exhaust port, and air compressor cylinder in line with said power cylinder, a compressor piston rigid with said power piston and fitting slidably in said corn pressor cylinder, an annular casing surrounding said power cylinder, whereby compressed air from said casing can enter said power cylinder through said air intake port thereof, said compressor cylinder directly adjoining said annular casing, with a partition between said compressor cylinder and said reservoir portion, and valve means in said partition for letting compressed air flow unidirectionally from said compressor cylinder to said casing, 'a' conduit extending between said respective annular casings ofsaid elementary auto-generators, whereby the whole of said two annular casings and said conduit forms a compressed air reservoir and air under pressure is fed into said reservoir from the outside thereof by said compressor pistons and cylinders and said valve means, compressed air being compelled to flow through said conduit on its way toward said air intake port and air cooling means in said conduit, said two elementary auto-generators being adjusted to work in phase opposition, i. c. with a phase difference of 180.

2. An auto-generator of hot gases under pressure which comprises, in combination, two elementary auto-generators including each at least one internal combustion power cylinder provided with at least one air intake port and one exhaust port, a power piston freely movable in said cylinder, means for collecting the hot gases under pressure from said exhaust port, and air compressor cylinder in line with said power cylinder, a compressor piston rigid with said power piston and fitting slidably in said compressor cylinder, an annular casing surrounding said power cylinder, whereby compressed air from said casing can enter said power cylinder through said air intake port thereof, said compressor cylinder directly adjoining said annular casing, with a partition between said compressor cylinder and said reservoir portion, and valve means in said partition for letting compressed air flow unidirectionally from said compressor cylinder to said casing, a conduit extending between said respective annular casings of said elementary auto-generators, whereby the whole of said two annular casings and said conduit forms a compressed air reservoir and air under pressure is fed into said reservoir from the outside thereof by said compressor pistons and cylinders and said valve means, compressed air being compelled to flow through said conduit on its way toward said air intake port and a liquid cooled coil in said conduit, said two elementary auto-generators being adjusted to work in phase opposition, i. e. with a phase difference of 180".

References Cited in the file of this patent UNITED STATES PATENTS 2,292,233 Lysholm Aug. 4, 1942 2,408,031 Beale Sept. 24, 1946 2,408,089 Muntz Sept. 24, 1946 2,442,470 Pescara June 1, 1948 2,466,255 Mercier et al Apr. 5, 1949 2,473,204 Huber June 14, 1949 2,605,605 Huber Aug. 5, 1952 2,654,355 Scheiterlein Oct. 6, 1953 FOREIGN PATENTS 556,454 Great Britain Oct. 6, 1943 

